DE102017200822A1 - Ventilation device for an interior of a motor vehicle and method for operating such a ventilation device - Google Patents

Abstract

The invention relates to a ventilation device (19, 30) for an interior (16) of a motor vehicle, comprising a duct system comprising at least one air duct (20) and having a blower (1) by means of which an air flow can be generated in the duct system. In order to allow active ventilation of the interior (16) with a particularly low volume, at least one first sound transducer (24, 26) of the ventilation device (19, 30) is provided, by means of which a sound pressure in the duct system can be detected and a sound pressure corresponding to the detected sound pressure Signal to at least one second sound transducer (25, 27) of the ventilation device (19, 30) can be transmitted. By means of the at least one second sound transducer (25, 27), a counter sound pressure for reducing the sound pressure can be generated as a function of the signal in the duct system.

Description

The invention relates to a ventilation device for an interior of a motor vehicle according to the preamble of patent claim 1 and a method for operating such a ventilation device according to claim 7.

Ventilators, air conditioners and the like found in automobiles today are designed for a wide range of different conditions. At least over a large part of the corresponding operating conditions, a fan noise of the ventilation device or air conditioning system dominates the overall acoustic impression for respective vehicle occupants. Often there is only very limited space for known passive acoustic measures, such as absorbers available to address this problem of undesirable high volume of the ventilation device. This problem is exacerbated currently and probably in the future car development by an observable and expected increasing distribution of electrified vehicles and pure electric cars, in which the known from conventional cars, there omitted from the respective combustion engine masking noise eliminated.

The fan noise is inherently associated with the indispensable for ventilation facilities function of air flow generation. This noise can not be reduced, for example, by reducing a speed of the fan sufficiently. In addition, respective air ducts and air distribution elements carry passive, that is, for example, without being actively moved to be or become, to the perceptible in the interior of the motor vehicle total noise of the respective ventilation device or air conditioning at. Often there is also the problem that in particular by air distribution elements and / or measures is not only an acoustic transmission of noise of the ventilation device or air conditioning in the interior of the motor vehicle with an undesirably high level results there, but also often as a distracting or unpleasant perceived noise quality.

Object of the present invention is to enable active ventilation of an interior of a motor vehicle with a particularly low volume or particularly high-quality noise image.

This object is achieved by a ventilation device with the features of claim 1 and a method according to claim 7zumbetrieb for operating such a ventilation device. Advantageous embodiments, developments and embodiments of the invention are specified in the dependent claims, the description and the drawings.

A ventilation device according to the invention for an interior of a motor vehicle or for ventilating an interior of a motor vehicle comprises a duct system, which in turn has at least one air duct, and a blower, by means of which an air flow in the duct system can be generated. In order to enable active ventilation of the interior of the motor vehicle with a particularly low volume, it is provided according to the invention that the ventilation device comprises at least a first sound transducer and at least one second sound transducer. By means of the at least one first sound transducer, a sound pressure in the channel system, in particular in the air duct, can be detected. The at least one first sound transducer provides a signal or output signal which corresponds to the detected sound pressure and / or correlates with it. This signal can then be transmitted directly or indirectly to the at least one second sound transducer of the ventilation device. The signal can first be transmitted from the at least one first sound transducer to an evaluation device or a control unit, which processes the signal and in turn transmits a corresponding control signal to the at least one second sound transducer of the ventilation device. The evaluation device and / or the control unit may alternatively be considered as part of the at least one first and / or the at least one second sound transducer or be such a part. By means of the at least one second sound transducer is in response to the signal or in response to the control signal in the channel system, in particular as close to the source, that is in a vicinity of the blower, a counter sound pressure for reducing the prevailing or existing sound pressure generated. In other words, the ventilation device according to the invention thus comprises an anti-noise system (ANC), which represents a system for active noise minimization or suppression.

The reduction of the sound pressure and thus the minimization or suppression of the sound or the corresponding noises is based on the functional principle of destructive interference. The ventilation device - or the anti-noise system - may have a functionally coupled to the at least one second sound converter controller. Advantageously, then, the at least one first sound transducer, the at least one second sound transducer and the controller may be formed or arranged as part of a control loop. By the Ventilation device can thus automatically, that is, without active action, for example, an occupant of the motor vehicle, with respect to a generated by the ventilation device in the interior noise or noise levels or a corresponding noise volume optimized control and / or control of the ventilation device, in particular the at least one second sound transducer done ,

The ventilation device according to the invention is advantageously designed and adapted to reduce the sound pressure or sound pressure level in the duct system of the ventilation device, resulting in a direct reduction of the sound pressure or the sound pressure level in the interior of the motor vehicle. From the perspective of the respective occupant of the motor vehicle, a quieter active ventilation of the interior of the motor vehicle compared to known ventilation devices is thus provided. Due to the active and controlled control possibility of the at least one second sound transducer, the operating noise of the ventilation device according to the invention can not only be reduced, but selectively controlled or adjusted. As a result, a coupling between an acoustic transmission behavior, in particular of the duct system, and the perceptible noise quality of the ventilation device, which is known in the interior of the motor vehicle, can be reduced or at least partially eliminated in the case of known ventilation devices. The respective acoustic transmission behavior of the duct system and the ventilation device is substantially by their geometric shape and functionally necessary facilities and components, such as air distribution or air distribution elements, a flap box and the like, and thus by at least substantially necessary for the ventilation device or for example for climate comfort relevant functions facilities, Conditions and / or conditions determined.

In spite of these limitations and boundary conditions, the present invention makes it possible, particularly with regard to a respective shaping and / or arrangement of individual elements and components of the ventilation device, to achieve or enable greater freedom compared to conventionally known ventilation devices with simultaneously reduced volume and / or increased acoustic quality.

The at least one first sound transducer may be, for example, a microphone or include. The at least one second sound transducer may for example be a loudspeaker or comprise a loudspeaker. The signal corresponding to the detected sound pressure can be transmitted, for example, via a corresponding data line, wherein the at least one second sound transducer is set up to receive the signal or a corresponding control signal corresponding thereto. The at least one first sound transducer and / or the at least one second sound transducer may preferably be arranged in a vicinity of the blower. In such an arrangement, the sound generated by the blower or generated in or on the blower or a corresponding sound field is advantageously not or only to the smallest extent or extent influenced by other components or elements of the ventilation device, before the sound or the sound field on the at least a first sound transducer and / or meets the at least one second sound transducer. As a result, the reduction or reduction of the corresponding sound pressure provided according to the invention can be achieved or realized particularly simply and with particularly little effort. The effort can be kept small in particular by a near-fan arrangement of the ANC system in the ventilation device or in the channel system, since in this case for the ANC system particularly few active components are necessary.

The channel system may include one or more air channels. Different air ducts can lead, for example, to different air outlets or vents, through which the air flow from the duct system can pass into the interior of the motor vehicle or is coupled.

In a further advantageous embodiment of the present invention, it is provided that the at least one air duct is subdivided by at least one separating element into a plurality of partial channels which are at least partially air-impermeably delimited from one another, in particular parallel to a flow direction of the air flow. This subdivision is provided in particular in an area in which the sound or sound pressure is reduced or is intended to be reduced. In other words, two flow regions which are separate from one another at least in sections or in sections are formed or generated by the at least one separating element in the respective one air duct. Thus, the air flow flowing through the air duct in two partial air streams that do not influence one another, at least in regions, for example, can pass from the blower to an air outlet or outflow, which represents an end of the air duct facing away from the blower. The two partial air ducts may preferably be of the same shape and of the same cross-section, in particular they may run or be arranged parallel to one another.

The separating element may be, for example, a partition wall or an intermediate wall. The separating element can completely penetrate the air duct, for example, from one lateral or boundary surface to an opposite lateral or boundary surface. By dividing the air channel into two or more subchannels or chambers can be achieved or ensured particularly advantageous with the least possible effort training a flat sound field in the respective sub-channels. Such a planar sound field is characterized in that the same phase is given over the entire cross-sectional area of the respective sub-channel in each plane oriented perpendicular to the propagation direction of the air stream and of the respective sub-channel. In other words, in each such oriented perpendicular to the flow direction of the air flow plane or cross-sectional plane or surface of the sub-channel prevails at a given time at least substantially the same sound pressure. Thus, it is thus advantageous to determine the respective sound pressure in the entire cross-sectional plane of the sub-channel which intersects this measuring point by measuring the respective sound pressure in or at a single point. As a result, it is advantageously possible to minimize component and measurement expenditure. The formation of such a planar sound field may be dependent on a size and geometry or shape of the air channel or of the respective sub-channel. The arrangement and optionally a correspondingly adapted design of the at least one separating element in the air duct can advantageously be forced the formation of a flat Schallfels in the respective sub-channels, which advantageously the described Antischallmethodik for reducing the sound pressure by means of at least one second transducer particularly effective, predictable and can be selectively used or applicable.

In a further advantageous embodiment of the invention, it is provided that the ventilation device for each of the plurality of sub-channels comprises at least a first transducer for detecting the respective sound pressure in the sub-channel and at least one second transducer for generating the respective counter-sound pressure in the sub-channel for reducing the respective sound pressure. In other words, it is thus provided that the number of first sound transducers and the number of second sound transducers respectively correspond to at least the number of subchannels, wherein in each subchannel both at least one first and at least one second sound transducers are arranged. This advantageously allows a particularly targeted and precise use of the respective sound transducer, since in each case only in a narrowly limited area - namely just in the respective sub-channel - a sound pressure or sound field must be detected or monitored and influenced.

In a further advantageous embodiment of the present invention, it is provided that the at least one second sound transducer against an inner region of the air duct - or optionally against an inner region of a respective sub-channel - is delimited by a flow protection element which is acoustically permeable and at least substantially impermeable to the air flow , In other words, therefore, each of the second sound transducer is covered by the flow protection element, so that the air flow flowing through the air duct does not impinge directly on the respective second sound transducer. In this case, however, the respective counter-sound generated and emitted by the second sound transducer can pass through the respective flow protection element and enter the air duct in order to influence, in particular reduce, the sound pressure prevailing there, in particular caused by the fan. The flow protection element may, for example, be connected to a side wall or a housing of the air duct in a vicinity of the at least one second sound transducer. Since a respective shape of the at least one second sound transducer is predetermined at least essentially by the required functionality, the at least substantially freely deformable flow protection element can advantageously be effectively prevented by impinging the air flow on the at least one second sound transducer or by flowing around it At least a second transducer due to the air flow additional noise or additional noise occurs or is generated. Depending on the specific use, the flow protection element can be designed or adapted, for example, as a function of typical frequencies and / or flow conditions prevailing in the respective application area. The arrangement of the flow-damping element in front of the at least one second sound transducer is particularly advantageous for generating the anti-sound necessary for reducing the sound pressure. In this case, it is particularly advantageous to avoid a pressure loss in the region of the at least one second sound transducer. Such a pressure loss would have a negative effect on the noise source itself, in particular the fan, since this would have to be operated to compensate for the pressure loss, for example with higher power and thus higher volume.

In a further advantageous embodiment of the present invention, it is provided that the at least one second sound transducer from the air duct acoustically decoupled, in particular vibroacoustically decoupled, is stored. In other words, it is therefore provided that the at least one second transducer is not directly attached to the air duct, that is, for example, attached to a side or boundary wall or a housing of the air duct. As a result, it can be advantageously avoided that structure-borne noise is transmitted from the at least one second sound transducer to the air duct and / or, for example, a housing of an air conditioning unit, and can thus reach the interior of the motor vehicle. To achieve this, the at least one second sound transducer may for example be mounted or held on another element or component and / or indirectly or indirectly fixed or held by a corresponding damping element and thus be decoupled acoustically, in particular vibroacoustically. In a corresponding manner, it is preferably provided that the at least one second sound transducer is also mounted acoustically, in particular vibroacoustically, decoupled from the entire duct system and / or from the fan. As a result, it can be advantageously avoided that additional sound or additional noise is introduced into the interior of the motor vehicle through the operation of the at least one second sound transducer.

Advantageously, respective inner surfaces or conversions of the air duct, preferably of the entire duct system, are structurally adapted to the respective sound and flow conditions of the respective ventilation device. As a result, advantageously, a sound passage of the at least one second sound transducer can be avoided. In other words, it can thus be advantageously achieved that no additional sound is generated, radiated and / or introduced into the interior of the motor vehicle via the air duct or the duct system, which would not arise or would be present in an otherwise similar ventilation device without the respective at least a second sound transducer and / or the remaining elements and components of the ANC system.

In particular, the at least one second sound transducer is particularly preferably arranged such that no additional pressure loss in the air duct and / or in the duct system is caused or induced by the at least one second sound transducer and / or its arrangement. As a result, it can advantageously be ensured that an intended, intended or desired ventilation effect can be achieved, in spite of the provided at least one second sound transducer and / or despite the ANC system provided, for example, without an increase or an increase in the power of the fan.

In a further advantageous embodiment of the present invention, it is provided that the sound pressure in a frequency range of 600 Hz to 2500 Hz can be reduced by means of the at least one second sound transducer. This frequency range dominates the overall level, whereby sound pressure at higher frequencies can be reduced with passive acoustic measures. Overall, it has been shown that this frequency range is particularly relevant for an overall acoustic impression of the ventilation device. Due to the effectiveness of the at least one second sound transducer and the reduction of the sound pressure in this frequency range, therefore, a reduction of the perceptible noise or the perceptible volume of the ventilation device and thus an improved acoustic impression in the interior of the motor vehicle can be achieved particularly effectively.

An inventive method is used to operate a ventilation device according to the invention. In this case, therefore, the sound pressure in the channel system is detected by means of the at least one first sound transducer and the signal corresponding to the detected sound pressure is generated and transmitted to the at least one second sound transducer. By means of the at least one second sound transducer, a counter sound pressure or a counter sound for reducing the sound pressure is then generated as a function of the signal in the duct system.

In a further advantageous embodiment of the present invention, it is provided that a sound spectrum corresponding to the sound pressure is determined and the at least one second sound transducer is controlled in the generation of the counter-sound pressure as a function of the determined sound spectrum. In other words, therefore, a targeted influence in certain spectral or frequency ranges can be made or achieved. Thus, a targeted adaptation of a resulting sound spectrum of the ventilation device or an operating noise of the ventilation device can be achieved. Particularly preferably, the at least one second sound transducer for generating the counter-sound pressure can be controlled such that the sum or superimposition of the sound pressure and the counter-sound pressure is effectively effectively at least substantially white noise and / or noise usually defined as and / or perceived as high quality Signal results or sets. In any case, the resulting overall noise can be approximated to such noise as compared to a total noise not affected by the operation of the ANC system. This can be achieved, for example, by lowering the level in certain spectral regions and / or by spectral filling in other spectral regions. In other words, it is thus possible effectively to perform a spectral line filling of the specific sound spectrum.

For example, specific frequencies or frequency ranges with particularly high amplitudes can be specifically attenuated more strongly than frequencies or frequency ranges which already have a lower amplitude in the specific sound spectrum. This can advantageously be achieved a particular positive effect on each occupant of the motor vehicle. For example, a calming, relaxing and as little as possible distracting effect can be achieved, as a result of which overall increased safety when driving the motor vehicle in the traffic situation can be achieved.

In a further advantageous embodiment of the present invention, it is provided that the at least one second sound transducer is controlled in the generation of the counter-sound pressure as a function of a temperature of the air flow flowing through the air duct. Alternatively or additionally, the at least one second sound transducer in the generation of the counter-sound pressure in dependence on a setting of an air conditioning device of the ventilation device or the motor vehicle or in response to a set or predetermined for the interior target temperature and / or an actual temperature of the interior of the motor vehicle can be controlled , The resulting total or operating noise of the ventilation device can therefore be adapted to the respective temperature. As a result, by means of a corresponding control of the at least one second sound transducer, a temperature sensation of respective occupants of the motor vehicle can be influenced in a targeted manner. As a result, an air conditioning function can be advantageously supported and / or a certain level of comfort for the respective occupants of the motor vehicle can be achieved in a shorter time and / or with reduced air conditioning performance.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or in isolation.

• 1 in schematischer Darstellung eine Wirkkette einer Belüftung für einen Innenraums eines Kraftwagens;
• 2 in schematischer Darstellung ein erstes Beispiel einer Belüftungseinrichtung;
• 3 in schematischer Darstellung ein zweites Beispiel einer Belüftungseinrichtung;
• 4 in schematischer Darstellung eine diagrammatische Veranschaulichung eines Potentials zur Geräuschreduzierung einer Belüftungseinrichtung; und
• 5 in schematischer Darstellung eine diagrammatische Veranschaulichung eines frequenzabhängigen Dämpfungsverhaltens einer Belüftungseinrichtung ohne Reduktion eines Schalldrucks mittels eines Schallwandlers.

The invention will now be explained in more detail with reference to preferred embodiments and with reference to the drawings relating to the present invention. Show it:

• 1 a schematic representation of an action chain of ventilation for an interior of a motor vehicle;
• 2 a schematic representation of a first example of a ventilation device;
• 3 a schematic representation of a second example of a ventilation device;
• 4 schematically a diagrammatic illustration of a potential for noise reduction of a ventilation device; and
• 5 a schematic representation of a diagrammatic illustration of a frequency-dependent damping behavior of a ventilation device without reducing a sound pressure by means of a sound transducer.

Identical or functionally identical elements are each identified by the same reference numerals.

1 shows a schematic representation of an action chain of ventilation for an interior of a motor vehicle. An essential part of the ventilation is here a blower 1 , The fan 1 draws the air supplied by him through a suction 2 , wherein in a corresponding intake a pressure loss 3 occurs. An operation of the blower 1 conditionally a sound generation 4 in or on the blower 1 , Such a sound is generated or produced in a real motor vehicle in which the blower 1 can be arranged or installed, transmitted by acoustic transmission to other components and in other areas of the motor vehicle, transmitted or directed. This concerns on the one hand a sound transmission 5 from the blower 1 to an instrument panel 6 of the motor vehicle. On the other hand, there is a sound transmission 7 from the blower 1 to an air duct 8th , The air duct 8th can to the blower 1 be connected and serves to guide one of the blower 1 generated airflow.

When flowing through the air duct 8th by the blower 1 generated air flow it comes to a sound generation 9 , The formation of sound 9 For example, on or in a for steering and / or distribution of the air flow in the air duct 8th arranged flap box and / or further air guiding or air guiding elements by a respective flow or flow around and / or occurring turbulence occur. From the air duct 8th it comes to a sound transmission 11 to a vent 12 , which provides a transition or interface between the air duct 8th and a ventilated interior 16 of the motor vehicle. The vent 12 So it is from the means of the blower 1 generated air flow flows through and flows through, and it also here to a sound generation 13 comes. Furthermore, also occurs at the vent 12 a pressure loss 14 on.

From the vent 12 starting there is a sound transmission 15 on or in the interior 16 in which, for example, each occupant of the motor vehicle can stay. When entering or crossing the air flow into the interior 16 If the air flow widens and there is a pressure drop here as well 17 , It does, however, not only by the sound transmission 15 from the vent 12 Sound in the interior 16 introduced, but also by a sound transmission 18 from the instrument panel 6 ,

The so in different ways in the interior 16 guided, guided or introduced sound may optionally be recorded or perceived by the occupants. This can represent an undesirable influence or load on the occupants, for example, for safety and / or comfort reasons. In a variety of operating conditions, in particular the fan 1 , is due to the ventilation of the interior 16 caused or conditional reaching to the occupants sound in the interior 16 That is, for example, in a passenger compartment of the motor vehicle, by the blower 1 generated sound component dominates. This may be the case in particular at relatively low air volumes transported by the air flow and correspondingly low flow velocities. These conditions are typically given in a case of persistence, that is to say in a ventilation operation in which a given actual state prevails in the interior space 16 at least substantially maintained or maintained. Such an actual state, for example, an oxygen concentration and / or an air temperature in the interior 16 affect.

By targeted elimination or reduction of the operation of the blower 1 generated or conditional sound or the corresponding noise can therefore advantageously in a particularly large number of operating conditions and situations, which typically make up a significant proportion of time a service life of the motor vehicle, a particularly effective reduction of the acoustic load in the interior 16 be achieved. Such a reduction of the acoustic load can be particularly effective, for example by means of a schematic representation in 2 shown first ventilation device 19 be achieved. The first aeration device 19 in the present case comprises the blower 1 and an adjoining this air duct 20. The air duct 20 can be part of the air duct 8th and thus, for example, be part of a more extensive, optionally branched channel system. The by means of the blower 1 Airflow generated can be the air duct 20 flow through and through this, for example, to the vent 12 be guided. The vent 12 For example, for a central arrangement in or on the instrument panel 6 or for a lateral arrangement in an edge region of the instrument panel 6 be provided. Basically, the air duct 20 have any shape or extent and transport or direct the air flow, for example, to any point of the motor vehicle.

In the present case is the air duct 20 through a separating element 21 into a first subchannel 22 and a second subchannel 23 divided. Preferably, the two sub-channels 22 . 23 be of the same size and shape and of the same cross section and / or extend parallel to each other. Through the separator 21 will also be that of the blower 1 divided airflow generated so that the two sub-channels 22 . 23 preferably flows through equal parts or equally. However, it is alternatively possible, the two sub-channels 22 . 23 specifically designed to make different and / or specifically to flow through different streams or to flow through. This can, for example, by design restrictions, such as certain space or packaging requirements of the motor vehicle, or about an asymmetry in the air duct 8th be made conditional or necessary.

By dividing or dividing the air duct 20 in the two subchannels 22 . 23 can be effected or ensured that, in particular by the blower 1 originating sound in each of the two subchannels 22 . 23 forms a flat sound field. Such a flat sound field is mathematically mathematically, in a planning and in a specific application technically very easy to control.

Furthermore, the first ventilation device in the present case comprises two first sound transducers and two second sound transducers. A first of the first two sound transducers is here as the first microphone 24 formed, which in or on the first sub-channel 22 is arranged. By means of the first microphone 24 may be one in the first subchannel 22 prevailing sound pressure can be detected or measured. Because of the constructive and geometric design of the air duct 20 in the two subchannels 22 . 23 during operation of the fan 1 a respective even sound field arises or is present, here is the single first microphone 24 for the determination of this plane sound wave or the corresponding sound pressure sufficient, as over an entire cross-sectional area of the first sub-channel 22 - And analogous over an entire cross-sectional area of the second sub-channel 23 - at least substantially and for practical applications exactly the same in each case, that is, for a given time spatially constant, sound pressure prevails.

The one by the first microphone 24 measured or determined sound pressure can be converted into a corresponding signal to this and transmitted, for example, to a controller, not shown here or a control unit not shown here. Depending on this signal, a first of the two second sound transducers, which in the present case is the first loudspeaker, can be controlled by the controller or the control unit 25 is formed, controlled or controlled. The first speaker 25 is here so within the air duct 20 arranged that one from the first speaker 25 generated sound in the first sub-channel 22 is emitted or emitted. The first speaker 25 is controlled in such a way that the sound emitted by it out of phase with the sound propagating along the first sub-channel 22 from the blower 1 starting propagating sound is. The one from the first speaker 25 emitted sound thus represents a counter-sound, which is due to an interaction between itself from the blower 1 starting along the first sub-channel 22 spreading sound and that of the first speaker 25 generated total or effectively a total sound or a total operating noise of the first ventilation device 19 results or sets. This overall operating noise is reduced or reduced in its volume or its sound pressure compared to an operating noise of the first ventilation device 19 which works without the use of the first microphone 24 and the first speaker 25 would give or set.

In an analogous or corresponding manner, the second of the first sound transducers are present as a second microphone 26 and the second of the two second transducers as the second speaker 27 educated. The second microphone 26 is for capturing or measuring yourself from the blower 1 proceeding along the second subchannel 22 propagating sound in or on the second subchannel 23 arranged. Also the second microphone 26 For example, a signal corresponding to the sound or sound pressure detected by it can be transmitted to the or a controller or to the or a control unit. Depending on this, from the second microphone 26 transmitted signal becomes the second speaker 27 controlled or controlled, so that the counter-sound generated by this in the second sub-channel 23 from the blower 1 starting propagating sound pressure reduced, reduced or at least partially canceled.

Overall, the two microphones 24 . 26 , the controller or the controller or the control units and the two speakers 25 . 27 So an antinoise or anti-noise system (ANC system, English "active noise cancellation") for active noise cancellation. This ANC system can ultimately do this in the interior 16 the motor vehicle operating noise of the first ventilation device 19 be reduced.

In the present case, the first ventilation device comprises 19 furthermore a first flow protection element 28 and a second flow protection element 29 , The first flow protection element 28 covers the first speaker here 25 against the first subchannel 22 and / or against that of the blower 1 generated airflow. This air flow is thus through the first flow protection element to the first speaker 25 steered, guided or guided around, so he does not go directly to the first speaker 25 incident. As a result, an accidentally caused by such an impact sound generation can be advantageously avoided. In the same way, the second flow protection element covers 29 the second speaker 27 against the second subchannel 20 and / or against the flowing through this proportion of the blower 1 generated airflow from.

The two flow protection element each 28, 29 are at least substantially for that of the blower 1 generated airflow impermeable. At the same time, the two flow protection element 28 . 29 however, for each of the first speaker 25 or from the second speaker 27 generated counter sound permeable. The at least substantially given permeability of the flow protection elements 28 . 29 for the air flow may mean, for example, that in a one-sided loading of the respective flow protection element 28 . 29 with the air flow, a respective resulting air flow velocity on a side facing away from the impact side of the respective flow protection element 28 . 29 is reduced by at least 75%, preferably by at least 90%, compared to a flow rate of the impinging air flow.

3 shows a schematic representation of a second ventilation device 30 , The second ventilation device 30 includes those already associated with the first aeration device 19 explained elements. Unlike the first aeration device 19 has the second ventilation device 30 however, an alternative arrangement or an alternative construction. In the present case, the second ventilation device 30 a first counter sounding 31 on which of the first subchannel 22 branches. The first speaker 25 is in a first subchannel 22 remote end portion of this first counter sounding 31 arranged. The first speaker of 20 generated counter sound is thus through the first counter sound 31 the first subchannel 22 fed. In this case, the first flow protection element 28 at or in a transition region between the first counter sounding feeder 31 and the first subchannel 22 arranged. The first flow protection element 28 So here can effectively a portion of a side wall of the first sub-channel 22 form. Preferably, the first flow protection element conceals 28 in the first subchannel 22 facing opening of the first counter sounder 31 Completely.

Like the first aeration device 19 is present also the second ventilation device 30 designed in essential parts symmetrical. Accordingly, it also branches off and from the second subchannel 23 provided a counter-sound supply, which as a second counter-sound supply 32 is designated. The second speaker 27 is in or at one of the second subchannel 23 remote end portion of the second counter sounding 32 arranged. The second speaker 27 is arranged or aligned so that the radiated by him counter sound through the second counter sound 32 in the second subchannel 23 to be led. The transition between the second counter sounding 32 and the second subchannel 23 is through the second flow protection element 29 covered.

Through the respective cover of the respective sub-channel 22 . 23 facing opening of the respective counter sound 31 . 32 by means of the flow protection elements 28 . 29 can be advantageously avoided a pressure loss in a flow past the air flow at these openings.

At the in 3 shown second ventilation device 30 is starting from the blower 1 in the flow direction of the air flow, the first speaker 25 in front of the first microphone 24 and the second speaker 27 before the second microphone change 20 and accordingly, the ANC system may operate based on feedback. Since the volume-reducing effect of the ANC system is particularly effective, especially in the hair condition, in which there are at least substantially uniform or constant noise or sound conditions or conditions and almost no rapid changes of these conditions or conditions occur, this arrangement of the ANC system can also Systems or of its individual components or elements in the second ventilation device 30 be used effectively in practice and

Regardless of the specific design or configuration can be by means of the respective ANC system not only a reduction of the sound pressure or the volume of the interior 16 reaching operating noise of the respective ventilation device 19 . 30 be achieved. Additionally or alternatively, a sound quality or a spectrum of the corresponding sound or operating noise can be influenced and modified in a targeted and controlled manner. In particular, an improved sound quality can be achieved, for example, by a spectral filling of the sound or frequency spectrum or of the operating noise. Likewise, one of an air conditioning state of the interior 16 and / or from a predetermined air conditioning target for the interior 16 dependent control of the speakers 25 . 27 and thus the generation of the respective counter-noise or counter-sound pressure possible. As a result, for example, a sound image of the respective ventilation device that supports a temperature sensation and / or an air conditioning effect 19 . 30 be generated or realized. These measures for adapting the noise pattern and / or for modification, in particular for improving the sound quality can be summarized under the term of active sound design (ASD, English "active sound design"). In order to achieve the best possible effect here, it may be provided, in particular for certain frequencies and / or frequency ranges, an acoustic transfer function of individual elements of the respective ventilation device 19 . 30 , such as the air duct 20, and / or the entire respective ventilation device 19 . 30 to investigate. The control or control of the speakers 25 . 27 can then take place in dependence on this acoustic transfer function.

The duct system, in particular the air duct 20 be prepared in whole or in part by means of a blow molding process. The channel system can be the first counter sounder 31 and / or the second counter sounding 32 include.

4 Fig. 11 is a diagrammatic illustration of a potential for reducing the noise of an indoor ventilation device 16 of the motor vehicle. On an abscissa is a frequency f of the ventilation device passing through sound in Hz. On an ordinate is a sound power P dB (A). A first curve of the diagram gives a frequency-dependent course of a passive sound power 33 which, with a passive flow through the blower 1 and a flap box of the respective aeration device without operation of an ANC system. A second curve of the diagram gives a frequency-dependent course of an operating sound power 34 at, which at a flow through the respective ventilation device during operation of the blower 1 - also without operated or activated ANC system - occurs. A marked area between the passive sound power 33 and the operating sound power 34 represents an ANC potential 35 which is the proportion of the operating sound power 34 indicates which is to be eliminated by the actively operated ANC system. A reduction of the sound power down to below through the passive sound power 33 given level is possible in principle, but especially in a near range of the blower 1 not necessary for an occupant-effective noise reduction. As shown in the illustration 4 can be seen, in particular in a frequency range between about 600 to 700 Hz and about 4500 Hz, in particular in a frequency range between 900 Hz and 2500 Hz, a significant potential for noise reduction.

5 Fig. 12 is a diagrammatic illustration of a frequency-dependent attenuation behavior of a non-ANC system ventilation device. Again, the frequency is on an abscissa f in Hz and according to a logarithmic scale. On an ordinate is in the in 5 diagram shown an insertion insulation IL (English "insertion loss") in dB. Illustrated here is on the one hand an unedited course 36 , which results without passive passive acoustic material. On the other hand, an uninterrupted course 37 shown, which results with a passive sound-absorbing and / or sound-absorbing acoustic material. Clearly recognizable is a significant collapse of the insertion insulation IL in a frequency range around 1600 Hz, which is due to the respective geometry, in particular the respective cross-sectional area, of the respective air duct. Accordingly, a corresponding preferred effective range 38 of the respective ANC system is marked.

LIST OF REFERENCE NUMBERS

1

fan

2

aspiration

3

pressure drop

4

sound generation

5

sound transmission

6

dashboard

7

sound transmission

8th

air duct

9

sound generation

10

pressure drop

11

sound transmission

12

vent

13

sound generation

14

pressure drop

15

sound transmission

16

inner space

17

pressure drop

18

sound transmission

19

first ventilation device

20

air duct

21

separating element

22

first subchannel

23

second subchannel

24

first microphone

25

first speaker

26

second microphone

27

second speaker

28

first flow protection element

29

second flow protection element

30

second ventilation device

31

first counter sounding

32

second counter-sounding

33

passive sound power

34

Operating sound power

35

ANC potential

36

unequaled course

37

insulated course

38

effective range

f

frequency

P

sound power

IL

Einfügedämmung

Claims (9)

Ventilation device (19, 30) for an interior (16) of a motor vehicle, comprising a duct system comprising at least one air duct (20) and having a blower (1) by means of which an air flow can be generated in the duct system, characterized by at least one first sound transducer ( 24, 26) of the ventilation device (19, 30), by means of which a sound pressure in the channel system can be detected and a signal corresponding to the detected sound pressure to at least one second sound transducer (25, 27) of the ventilation device (19, 30) can be transmitted, by means of which depending on the signal in the channel system Counter sound pressure for reducing the sound pressure can be generated. Ventilation device (19, 30) according to Claim 1 , characterized in that the at least one air duct (20) by means of at least one separating element (21) in a plurality, in particular parallel to a flow direction of the air flow, at least partially air-impermeable to each other delimited sub-channels (22, 23) is divided. Ventilation device (19, 30) according to Claim 2 , characterized in that the ventilation device (19, 30) for each of the plurality of sub-channels (22, 23) at least one first sound transducer (24, 26) for detecting the respective sound pressure in the sub-channel (22, 23) and at least one second sound transducer ( 25, 27) for generating the respective counter-sound pressure in the sub-channel (22, 3) for reducing the respective sound pressure. Ventilation device (19, 30) according to any one of the preceding claims, characterized in that the at least one second sound transducer (25, 27) is delimited against an inner region of the air duct by a flow protection element (28, 29) which is acoustically permeable and at least for the air flow is essentially impermeable. Ventilation device (19, 30) according to one of the preceding claims, characterized in that the at least one second sound transducer (25, 27) is mounted acoustically decoupled from the air duct (20). Ventilation device (19, 30) according to one of the preceding claims, characterized in that the sound pressure in the frequency range from 600 Hz to 2500 Hz can be reduced by means of the at least one second sound transducer (25, 27). A method of operating a ventilation device (19, 30) according to one of the preceding claims, in which - The sound pressure in the channel system by means of the at least one first sound transducer (24, 26) detected and generates the signal corresponding to the detected sound pressure and transmitted to the at least one second sound transducer (25, 27), and - By means of the at least one second sound transducer (25, 27) in response to the signal in the channel system, a counter-sound pressure for reducing the sound pressure is generated. Method according to Claim 7 , Characterized in that to the sound pressure corresponding sound spectrum (36, 37) is determined and the at least one second sound transducer (25, 27) in the generation of anti-noise pressure in response to the determined noise spectrum (36, 37) is controlled. Method according to one of Claims 7 and 8th , characterized in that the at least one second sound transducer (25, 27) is controlled in the generation of the counter-sound pressure as a function of a temperature of the air flow.

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